生物酶/γ-Al2O3小球催化氧化柴油脱硫性能研究

通过吸附法将生物酶负载在γ-Al₂O₃小球载体上,并对生物酶/γ-Al₂O₃及载体进行扫描电镜(SEM)、比表面积分析(BET)、傅里叶红外光谱(FT-IR)及圆二色谱(CD)表征。结果表明:生物酶被吸附在载体上。将制备的生物酶/γ-Al₂O₃催化真实柴油氧化脱硫,考察了反应温度、反应流速和酶溶液浓度对真实柴油脱硫效果的影响,并对脱硫效果进行定性及定量分析;进一步对脱硫工艺条件进行响应面设计优化,找出最优反应条件。实验结果显示:反应温度49℃、反应流速1.0 mL/min、酶溶液浓度15.5%(酶载量为28.13 g),得出的最优脱硫率为93.16%;最后考察了该固定化酶的重复使用性能,该催化剂使用7次活性无明显降低,表明该固定化酶催化氧化柴油脱硫效果显著,具有潜在的工艺应用价值。     

稗属杂草对水稻生长发育和产量的影响

以新两优6号(籼稻)和南粳46(粳稻)为材料,自水稻移栽至成熟分别与无芒稗(T₁)、稗(T₂)、西来稗(T₃)和光头稗(T₄)共生,稗草密度为6株·m^-2,以无稗草水稻处理为对照,研究不同稗草对水稻生长发育和产量的影响.结果表明：与对照相比,不同稗草对水稻的干扰表现不同,T₁、T₂、T₃处理使籼稻产量分别下降19.2%、10.8%、21.9%,使粳稻产量分别下降39.7%、25.3%、47.3%,但T₄处理对2个水稻品种的产量均无显著影响.水稻和稗草共生过程中,T₁、T₂和T₃处理显著降低了水稻成熟期的干物质积累量及灌浆期的剑叶光合速率、根系氧化力和籽粒ATP酶活性,降低幅度为T₃>T₁>T₂,T₄处理与对照差异不显著;各处理对水稻最终分蘖数和株高均无显著影响.表明4种稗草对水稻生长的影响由强到弱表现为：T₃>T₁>T₂>T₄,稻 稗共生时水稻剑叶光合速率、根系氧化力和籽粒ATP酶活性降低是导致水稻生产力下降的重要原因.     

高浓度二氧化碳和臭氧对蒙古栎叶片活性氧代谢的影响

利用开顶箱熏蒸法,研究了高浓度O₃(≈80 nmol·mol^-1)和高浓度CO₂(≈700 μmol·mol^-1)及其复合处理对蒙古栎叶片活性氧代谢的影响.结果表明：高浓度O₃显著增加了蒙古栎叶片超氧阴离子(O₂^•)产生速率、过氧化氢(H₂O₂)和丙二醛(MDA)含量和电解质外渗率(P<0.05),显著降低了超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性和抗坏血酸(AsA)含量(P<0.05).高浓度CO₂对蒙古栎叶片活性氧代谢影响不显著.高浓度O₃和CO₂复合处理的叶片O₂^•产生速率、H₂O₂和MDA含量和电解质外渗率上升不明显,说明高浓度CO₂缓解了高浓度O₃对蒙古栎叶片的氧化胁迫.复合处理的叶片SOD、CAT、APX活性以及AsA和总酚含量显著高于O₃处理的叶片(P<0.05),说明高浓度CO₂缓解了高浓度O₃对叶片抗氧化系统的消极影响.     

水环境中活性氧的来源、种类及测定方法

各种环境介质和生命体中许多微观化学过程都与活性氧密切相关.本文介绍了水环境中活性氧的来源、种类和测定.它们主要包括:¹O₂(单线态氧)、O₂^-(超氧自由基)/HO₂·(氢过氧自由基)、·OH(羟基自由基)、H₂O₂、RO·(烷氧基)、ROO·(烷过氧基)和R·OH(氢过氧化物)等.其主要来源于辐射分解、热解和氧化还原法等.测定采用分子探针法、图谱法和酶法.     

大气CO2浓度缓增对稻田硝酸盐型甲烷厌氧氧化过程的影响

硝酸盐型甲烷厌氧氧化(AOM)是控制稻田甲烷排放的一种新途径,大气CO₂浓度升高会对稻田甲烷排放产生重要影响,但有关其对硝酸盐型AOM过程的影响知之甚少。本研究依托开顶式气室组成的CO₂浓度自动调控平台,采用¹³CH₄稳定性同位素示踪技术,从甲烷氧化活性、相关功能微生物Candidatus Methanoperedens nitroreducens (M. nitroreducens)-like古菌丰度与群落组成等方面,系统研究了稻田土壤中硝酸盐型AOM过程对大气CO₂浓度缓增的响应。试验设置背景CO₂浓度和CO₂浓度缓增处理(背景CO₂浓度基础上每年增加40 μL·L^-1,直至增幅达160 μL·L^-1)。结果表明: 稻田土壤硝酸盐型AOM速率为0.7～11.3 nmol CO₂·g^-1·d^-1;定量PCR结果显示,M. nitroreducens-like古菌mcrA基因丰度为2.2×10⁶～8.5×10⁶ copies·g^-1。与对照相比,CO₂浓度缓增处理使土壤中硝酸盐型AOM速率和M. nitroreducens-like古菌mcrA基因丰度均有一定幅度提高,特别是在5～10 cm深度下两者均显著提高。CO₂浓度缓增处理未显著改变M. nitroreducens-like古菌群落结构,但使其多样性显著降低。相关性分析表明,土壤有机碳含量可能是影响硝酸盐型AOM过程的重要因子。综上,大气CO₂浓度缓增在一定程度上促进了硝酸盐型AOM反应,暗示在未来气候变化背景下其在控制稻田甲烷排放中具有积极作用。     

花生根瘤菌类菌体氢氧化体系的研究

花生根瘤菌类菌体含有吸H₂酶,以O₂或亚甲蓝为电子受体均表现吸H₂活性。类菌体还原减氧化的吸收差示光谱在424、500、520、550、560、585及595 nm处呈现吸收峰,表明细胞色素c、b、和o参与H₂的氧化过程。CN-明显影响520、550、560 nm处的吸收峰,意味着有些细胞色素c和b对CN^-敏感,在H₂代谢中充当末端氧化酶的作用。抗霉素A、HONO、CN^-、N₃^-和DBMIB均强烈抑制吸H₂活性,但鱼藤酮不抑制吸H₂活性。说明细胞色素b、c、a和泛配参与H₂氧化的电子传递,而NADH脱氢酶不参与。花生根瘤菌类菌体的H₂氧化系统是个复杂具分支的电子传递体系。     

渠式生物膜氧化法处理生活污水的技术研究

研究了利用渠式生物膜法进行生活污水处理实验。该法结合了活性污泥法和生物膜法的优点,能有效处理城市生活污水,而且装置不设二沉池,占地面积少,基建投资省。实验测定了不同的水力停留时间(HRT)和进水负荷下的化学需氧量(COD_Cr)及氨氮(NH₃-N)浓度,并分析其对去除率的影响。结果表明,在实验设定的范围内,COD_Cr和NH₃-N去除率随着水力停留时间的增大而增大,而随着进水负荷的增大而相应的减少。在水温25℃,流量0.6L·min^-1,COD_Cr 100mg·L^-1,NH₃-N 15 mg·L^-1的条件下,污染物的去除率较高(COD_Cr为71%、NH3-N为36%),出水水质比较理想,可以达到景观、娱乐和冷却水等的用水标准。     

水稻土中CH4氧化的研究

在实验室条件下研究了水稻土中CH₄氧化的特性.结果表明,在早稻种植前采集的水稻土不能氧化大气中的CH₄,但当所供给的CH₄浓度>10μl·L^-1时,能迅速氧化CH₄,所供给的CH₄浓度越高,氧化CH₄的速度越大.经高浓度(>1000μl·L^-1)的CH₄预培养10d,可使本来不具有氧化大气CH₄能力的土壤氧化大气CH_4.大田CH₄排放通量高的水稻土,氧化CH₄的能力较大.     

沙棘果油对过氧化氢诱导氧化损伤的保护作用

沙棘(Hippophae rhamnoides)是一种具有药用价值的植物,沙棘果油具有抗氧化、抗炎症及抗肿瘤等多种药理作用。为了探讨沙棘果油对H₂O₂造成氧化性损伤的细胞生长的影响及其抗氧化性,该研究选择H₂O₂对RAW264.7细胞氧化损伤模型,通过DPPH(1,1-二苯基-2-三硝基苯肼)自由基清除实验检测沙棘果油体外抗氧化能力,用[3-(4,5-二甲基噻唑-2)2,5-二苯基四氮唑溴盐]MTT法和流式细胞仪检测超氧化物阴离子荧光探针(DHE)信号,分别检测不同浓度沙棘果油对H₂O₂损伤细胞的存活率和超氧化物阴离子水平。结果表明:(1)在DPPH自由基清除实验中,当沙棘果油浓度小于4.9%时,沙棘果油的抗氧化能力大于维生素C。(2)通过MTT法发现,浓度为3.125%的沙棘果油对H₂O₂损伤细胞的存活率显著升高(P<0.01)。(3)从DHE检测发现,在同一检测时间点,随着沙棘果油浓度增加,DHE阳性细...     

甲烷厌氧氧化机理及其应用研究进展

甲烷是一种重要的温室气体, 研究证明甲烷厌氧氧化(AOM)对于降低全球甲烷的排放有着重要意义。参与AOM 反应的最终电子受体可分为三类, 即SO2– 4、NO₂^– /NO₃^–以及以Fe³⁺、Cr⁵⁺等为代表的金属离子。本文基于甲烷厌氧氧化过程所利用的电子受体的差别, 结合不同类型AOM 反应微生物的基因型分析, 阐述了AOM 过程的反应机理、相关的微生物种类及其代谢途径。其中对AAA(AOM-associated archaea, 属于ANME-2d)的分离培养, 以及其利用硝酸盐、Fe³⁺、Cr⁵⁺等离子氧化甲烷的研究对认识AOM 反应机理和AOM 的实际应用有很大推动作用。本文还介绍了AOM 过程在环境污染控制领域实际应用中的最新研究进展, 对AOM 的实际应用及其在节能减排上的价值进行展望。AOM 过程的进一步研究对拓宽该过程的工程应用以及对正确认识全球碳、氮、硫循环均有着重要意义。     

In Vivo Metabolism of the Vitamin D Analog, 22-Oxacalcitriol: Evidence for Side-chain Truncation and 17-Hydroxylation

After intravenous administration of the vitamin D₃ analog, 22-oxacalcitriol (OCT), to normal rats plasma metabolites were investigated by HPLC, GC-MS and LC-MS. Five side-chain oxidation metabolites, 24R(OH)OCT, 24S(OH)OCT, (25R)-26(OH)OCT, (25S)-26(OH)OCT and 24oxoOCT, were identified by comparison with the corresponding synthetic compounds. These side-chain oxidation metabolites were similar to those of calcitriol [1,25(OH)₂ vitamin D₃] described previously. Besides these five metabolites, two unique side-chain cleavage metabolites, 20S(OH)-hexanor-OCT and 17,20S(OH)₂-hexanor-OCT, were identified as main metabolites in plasma by GC-MS and LC-MS using a specific chemical reaction. Our studies suggest that OCT is extensively metabolized and circulates in blood as a number of metabolites as well as unchanged OCT. This metabolism includes both unique pathways of C₂₃-O₂₂ cleavage and 17-hydroxylation, in addition to the side-chain oxidation metabolites similar to those of 1,25-(OH)₂D₃.     

Increased biological potency of hexafluorinated analogs of 1,25-dihydroxyvitamin D3 on bovine parathyroid cells

1,25-dihydroxyvitamin D₃ (1,25-(OH)₂D₃) is known to be involved in regulating the proliferation of parathyroid cells and PTH synthesis through reactions involving its nuclear receptor. We evaluated the effects of 1,25-(OH)₂D₃ and its hexafluorinated analog, 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D₃ (26,27-F₆-1,25-(OH)₂D₃), on parathyroid cells. The 1,25-(OH)₂D₃ and 26,27-F₆-1,25-(OH)₂D₃ each inhibited [³H]thymidine incorporation and ornithine decarboxylase (ODC) activity, which is important in cell proliferation, in primary cultured bovine parathyroid cells. The inhibitory effect of 26,27-F₆-1,25-(OH)₂D₃ on PTH secretion from parathyroid cells was significantly more potent than that of 1,25-(OH)₂D ₃ between 10⁻¹¹ M and 10⁻⁸ M. Study of 26,27-F₆-1,25-(OH)₂D₃ metabolism in parathyroid cells in vitro elucidated its slower degradation than that of 1,25-(OH)₂D₃. After 48 h of incubation with [1β-³H]26,27-F₆-1,25-(OH)₂D₃, two HPLC peaks, one for [1β-³H]26,27-F₆-1,25-(OH)₂D₃, and a second larger peak for [1β-³H]26,27-F₆-1,23(S),25-(OH)₃D₃, were detected. No metabolites were detected after the same period of incubation with 1,25-(OH)₂[26,27-³H]D₃. We observed that 26,27-F₆-1,23(S),25-(OH)₃D₃ was as potent as 1,25-(OH)₂D₃ in inhibiting the proliferation of parathyroid cells.

Data suggest that the greater biological activity of 26,27-F₆-1,25-(OH)₂D₃ is explained by its slower metabolisms and by the retention of the biological potency of 26,27-F₆-1,25-(OH)₂D₃ even after 23(S)-hydroxylation.     

Methane-dependent nitrate production by a microbial consortium enriched from a cultivated humisol

Abstract A consortium was enriched from a humisol incubated with 3.6 kPa CH₄ and NH₄⁺. This consortium oxidized NH₄⁺ to NO₂⁻ and NO₃⁻ (NO₃⁻/NO₂⁻ ratio about 20) with smaller amounts of N₂O. This oxidation stopped in the stationary phase after depletion of CH₄. CH₃OH or CO₂ did not support oxidation. Growth and resting cell experiments suggested that nitrification was associated with methanotrophic activity and that chemoautotrophic nitrifiers were absent.     

Use of genetically modified mice to examine the skeletal anabolic activity of vitamin D

We employed genetically modified mice to examine the role of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] on skeletal and calcium homeostasis. In mice expressing the null mutation for 25-hydroxyvitamin D 1 hydroxylase (1OHase^−/−), or the vitamin D receptor (VDR^−/−), 1,25(OH)₂D₃ and calcium were both required for optimal epiphyseal growth plate development, serum calcium and phosphorus alone were sufficient to mineralize skeletal tissue independent of 1,25(OH)₂D₃ and the VDR, and endogenous 1,25(OH)₂D₃ and the VDR were essential for baseline bone formation. In 2-week-old 1OHase^−/− mice and in 2-week-old mice homozygous for the PTH null mutation(PTH^−/−), PTH and 1,25(OH)₂D₃ were each found to exert independent and complementary effects on skeletal anabolism, with PTH predominantly affecting appositional trabecular bone growth and 1,25(OH)₂D₃ influencing both endochondral bone formation and appositional bone growth. Endogenous 1,25(OH)₂D₃ maintained serum calcium homeostasis predominantly by modifying intestinal and renal calcium transporters but not by producing net bone resorption. Administration of exogenous 1,25(OH)₂D₃ to double mutant PTH^−/−1OHase^−/− mice produced skeletal effects consistent with the actions of endogenous 1,25(OH)₂D₃. These studies reveal an important skeletal anabolic role for both endogenous and exogenous 1,25(OH)₂D₃ and point to a potential role for 1,25(OH)₂D₃ analogs in the treatment of disorders of bone loss.     

Screening of Vitamin D activity (VDA) of Solanum glaucophyllum leaves measured by radioimmunoassay (RIA)

The ingestion of Solanum glaucophyllum (SG) causes a calcinosis of cattle named Enteque Seco (ES). The toxic principle is the 1,25-(OH)₂D₃, mainly conjugated as glycoside. This study aims to validate a simple novel method of evaluation of the VDA of SG leaves. Aqueous extracts of SG were purified using C₁₈ minicolumns and assayed by RIA with an antibody raised in rabbits by injection of the acid—C22, 1-(OH)Vitamin D₃. Data were expresed as glycoside equivalent to 1,25-(OH)₂D₃ in ng/g of dry leaves. We compared this data with 1,25-(OH)₂D₃ levels measured, in the same samples, by liquid chromatography (HPLC) after enzyme cleavage. This procedure involved the incubation of SG leaves with rumen fluid, followed by C₁₈-OH solid phase extraction. The 1,25-(OH)₂D₃ fraction was run by HPLC and detection was achieved using a photodiode array detector. Data were expressed as micrograms of 1,25-(OH)₂D₃/g dry leaves. A significant regression of 1,25-(OH)₂D₃ levels (Y) as a function of glycoside RIA 1,25-(OH)₂D₃ equivalents (X) was found: Y = 12.02 + 0.35X [R = 0.81; P = 0,0002; N = 15], allowing us to conclude that this novel assay could be used to estimate the amount of this active principle contained in SG leaves.     

Activity and composition of ammonia oxidizing bacterial communities and emission dynamics of NH3 and N2O in a compost reactor treating organic household waste

Aims:  To monitor emissions of NH₃ and N₂O during composting and link these to ammonia oxidation rates and the community structure of ammonia oxidizing bacteria (AOB).
Methods and Results:  A laboratory-scale compost reactor treating organic household waste was run for 2 months. NH₃ emissions peaked when pH started to increase. Small amounts of N₂O and CH₄ were also produced. In total, 16% and less than 1% of the initial N was lost as NH₃-N and N₂O-N respectively. The potential ammonia oxidation rate, determined by a chlorate inhibition assay, increased fourfold during the first 9 days and then remained high. Initially, both Nitrosospira and Nitrosomonas populations were detected using DGGE analysis of AOB specific 16S rRNA fragments. Only Nitrosomonas europaea was detected under thermophilic conditions, but Nitrosospira populations re-established during the cooling phase.
Conclusions:  Thermophilic conditions favoured high potential ammonia oxidation rates, suggesting that ammonia oxidation contributed to reduced NH₃ emissions. Small but significant amounts of N₂O were emitted during the thermophilic phase. The significance of different AOBs detected in the compost for ammonia oxidation is not clear.
Significance and Impact of Study:  This study shows that ammonia oxidation occurs at high temperature composting and therefore most likely reduces NH₃ emissions.     

H2 and CO2 production from methanol or formaldehyde by the methanogenic bacterium strain Gö1 treated with 2-bromoethanesulfonic acid

Abstract In cell suspensions of the methanogenic bacterium strain Gö1 or Methanosarcina barkeri H₂ formation from methanol in the presence of 2-bromoethanesulfonic acid (BES) was strictly dependent on sodium ions; apparent K _S for Na⁺, 1.3±0.3 mM.H₂ formation was inhibited by the uncoupler tetrachlorosalicylanilide (TCS), but this inhibition could be temporarily overcome, when a sodium pulse (100 mM) was given to the cell suspension. On the other hand, H₂ formation from formaldehyde in the presence of BES (rate: 300 nmol H₂/h·mg protein as compared to 25 nmol H₂/h·mg protein from methanol) was not sodium-dependent, not TCS-sensitive and not inhibited by addition of monensin. H₂ formation was accompanied by CO₂ formation in stoichiometric amounts, 3 H₂:1 CO₂ for methanol and 2 H₂:1 CO₂ for formaldehyde oxidation.     

X-ray absorption fine structure study of the atomic and electronic structure of molybdenum disulfide intercalation compounds with transition metals

The local structures of ‘host’ and ‘guest’ layers of MoS₂ intercalated with M(OH)₂ (M=Mn, Co and Ni) prepared via interaction of single-layer MoS₂ dispersions and solutions of M²⁺ salts were studied by X-ray absorption spectroscopy. According to M K-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) results, the electronic structure and atomic environment of the M atoms in the intercalates are similar to that of the crystalline hydroxides M(OH)₂. In the Ni intercalate, Mo K-edge EXAFS revealed a structural change of the ‘host’ MoS₂ layers similar to that reported for water dispersions of MoS₂ single layers. S K-edge XANES data indicate that the change is associated with increased electron density on the S atoms in the matrix. SO₄²⁻ and Mo″⁻ (4 < n < 6) were detected in the intercalated materials exposed to air, suggesting that transition metal intercalation may increase the susceptibility of the MoS₂ layers to oxidation.     

Caffeine decreases vitamin D receptor protein expression and 1,25(OH)2D3 stimulated alkaline phosphatase activity in human osteoblast cells

Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300 mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D₃ (1,25(OH)₂D₃) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)₂D₃, VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)₂D₃ mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10 mM) on 1,25(OH)₂D₃ induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)₂D₃ induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)₂D₃ induced VDR expression and at concentrations of 1 and 10 mM, VDR expression was decreased by about 50–70%, respectively. In addition, the 1,25(OH)₂D₃ induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)₂D₃ stimulated VDR protein expression and 1,25(OH)₂D₃ mediated actions in human osteoblast cells.     

Synergistic anti-proliferative effects of vitamin D derivatives and 9-cis retinoic acid in SH-SY5Y human neuroblastoma cells.

This study examines the effect of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], 24,25-dihydroxyvitamin D₃ [24,25(OH)₂D₃], two vitamin D analogues (KH 1060 and EB 1089, which are 20-epi-22-oxa and 22,24-diene-analogues, respectively), 9-cis retinoic acid and all-trans retinoic acid on proliferation of SH-SY5Y human neuroblastoma cells, after treatment for 7 days. Cell number did not change when the cells were incubated with 1, 10 or 100 nM 1,25(OH)₂D₃ or its derivatives, but significantly decreased in the presence of the two retinoids (0.001–10 μM final concentration). A synergistic inhibition was observed, when SH-SY5Y cells were treated combining 0.1 μM 9-cis retinoic acid and 10 nM 1,25(OH)₂D₃ or 10 nM KH 1060, and 1 μM 9-cis retinoic acid and 10 nM 1,25(OH)₂D₃ or 10 nM EB 1089. Acetylcholinesterase activity showed a significant increase, in comparison with controls, after treatment of the cells for 7 days with 0.1 or 1 μM 9-cis retinoic acid, alone or combined with 10 nM 1,25(OH)₂D₃ or 10 nM KH 1060 or 10 nM EB 1089. This increase was synergistic, combining 1 μM 9-cis retinoic acid and 10 nM 1,25(OH)₂D₃ or EB 1089. The levels of the c-myc encoded protein remarkably decreased after treatment of SH-SY5Y cells for 1, 3, 7 days with 0.1 and 1 μM 9-cis retinoic acid, alone or combined with 10 nM 1,25(OH)₂D₃ or 10 nM KH 1060 or 10 nM EB 1089. In particular, the association of 1 μM 9-cis retinoic acid and 10 nM 1,25(OH)₂D₃ or 10 nM EB 1089 resulted in a synergistic c-myc inhibition, in comparison with that obtained in the presence of the retinoid alone. These findings may have therapeutic implications in human neuroblastoma.